With the advancement of light cured composite restorative dental materials, many dental materials have become much more viscous due to the higher levels of filler loading. Although the higher filler loading increases the strength and reduces the polymerization shrinkage of these materials, they have become very difficult to extrude from the compules they are packaged in. In addition, due to their clay-like handling characteristics they are also difficult to well adapt to the internal angles of the cavity preparation.
One method that assists in extruding highly viscous materials has been to heat the material prior to placement. Since most dental composite materials are packaged in molded plastic cartridges commonly referred to as compules, any heat from an external source needs to first overcome the thermal resistance or insulating nature of the plastics typically used to manufacture the compules. Prior art dental composite containers or compules are molded from plastic materials such as polyethylene, as well as polyvinyl chloride (PVC) and its derivatives.
One prior system includes a dispenser for heating and extruding dental material which includes drawbacks such as that the dispenser (holding and heating the compule) uses a dedicated microprocessor control circuit with an embedded thermocouple to control the current in the heater and in turn the temperature to which the composite material is heated. This arrangement adds significant cost to the manufacture of such a device. In addition, since the compule is molded from normal plastic material (e.g., polypropylene) which is a thermal insulator, the compule requires high power, high temperature and/or a lengthy heating time to overcome its thermal resistance. The composite material may then take a long time to reach the desired temperature.